This piece of code is in my textbook, but what I'm not understanding is the method TestPanels(). It has no return type AND no void. How can this happen? \[code\]public class TestPanels extends JFrame {public TestPanels() { JPanel p1 = new JPanel(); p1.setLayout(new GridLayout(4,3)); for (int i = 1; i <= 9; i++) { p1.add(new JButton(""+i)); } p1.add(new JButton(""+0)); p1.add(new JButton("Start")); p1.add(new JButton("Stop")); JPanel p2 = new JPanel(new BorderLayout()); p2.add(new JTextField("Time to be displayed here"), BorderLayout.NORTH); p2.add(p1, BorderLayout.CENTER); add(p2, BorderLayout.EAST); add(new JButton("Food to be placed here"), BorderLayout.WEST); }public static void main(String[] args) { TestPanels frame = new TestPanels(); frame.setTitle("The Front View of a Microwave Oven"); frame.setSize(400, 250); frame.setLocationRelativeTo(null); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.setVisible(true); }}\[/code\]